1. Field of the Invention
The present invention relates to the field of radio telecommunication apparatus used in a radio telecommunication system, and more particularly to a radio telephone apparatus such as a cellular mobile telephone apparatus.
2. Description of the Related Art
In the radio telecommunication apparatus such as a cellular mobile telephone apparatus (hereinafter simply called mobile telephone apparatus), a reception phone is generally silent when the call is originated and the call is terminated. For example, after a telephone number is dialed by the user of the mobile telephone, a reception phone is silent until a speech channel is established between the mobile telephone and a base station. The reception phone is also silent when the call is terminated by the other party or the communication channel line between the base station and the mobile telephone is automatically disconnected due to a trouble of an associated radio channel resulting from, for example, a fading.
It is difficult, from the human sense, to distinguish such a silent period from a silent period during the actual speech communication, which is occurred when the other party of the communication does not utter a sound. Thus, the user of the mobile telephone may carelessly get out of the automobile even while a speech communication link has been established. In this case, the other party feels unpleasant. Alternately, the user may forget the termination processing to release the communication link. This leads to an increase of communication fee.
Further, if the reception phone is silent for a period of time during the speech communication, the user of the mobile telephone would sometimes wonder whether or not the other party terminates the communication and then he or she off-hooks the handset. In this case, the other party also feels unpleasant.
In order to prevent such a mistake, a communication indicator lamp is provided with the conventional mobile telephone, which is turned on upon a depression of a calling start key and off upon the disconnection of the speech communication. However, since this indicator is turned on after the calling start key is depressed, it is not possible for the user to recognize whether or not the speech communication link is established. Further, since the visual indication is performed, the user must intentionally watch the indicator to ascertain whether or not the channel is connected.
As described above, in the conventional radio telecommunication apparatus, the user is not able to properly grasp the current status of the telecommunication apparatus unless he or she ascertains what is going on the line.